thru hull exhuast how much angle needed
 

ok gonna try and set the 454,s in my formula this weekend to mock up the engine compartment i have older center dump exhuast . Im going to run flex hose back to transom to the tips i have to cut holes for.. how much of a down hill angle do i need ? or how flat can the hose be any rule of thumb on this...

Merc actually had a drawing for this. The nice thing about following that, is if you decide later to go aftermarket, you can use off the shelf tailpipes.

I did a trial on mine with the small blocks and figure real quick that I had to have tall risers to get over the top of the steering...very tight fit. If I go low I am beneath the swim platform and underwater at rest. Right now I'm leaning towards the Y-Pipes.

if the angle is a little off between exh hose and tips the way they are mounted in transom, a guy on here had a good idea for a small angle elbow. take a piece of 4 inch stainless tubing, and cut it about 6 inches long with the cuts at a slight angle. then you can tilt the hose on the tubing for a 10 or 20 degree angle.

http://i35.photobucket.com/albums/d1...l/P1010380.jpg

http://i35.photobucket.com/albums/d1...l/P1010381.jpg

first one is bbc with a bravo one,second is sb or bb alpha one..funny thing is they both have the same measurements..most formulas have a higher (6'') spacer then the riser so the exhaust will fit into the silent thunder platform..if you dont have a silent thunder~~~~~~~~~~~~~~~~~~~~~~~

wait a min is this the 255 liberator???? your going to be close with the big blocks in their....

yes 255 liberator with big blocks..